The Histopathology Core will provide integral support for all 3 projects. This core will centralize the pathology resources for all of the projects of the PPG. This will result in cost savings, increased quality control and maximal comparability between the results of the projects. Key funcfions of the Core include: 1) expert advise in immunohistological aspects of experimental design to optimize results; 2) uniform tissue processing; 3) tissue secfioning (frozen sections and paraffin-embedded sections); 4) histochemical and immunohistochemical staining of tissue secfions; 5) pathological interpretation of fissue sections; 6) documentafion of the pathology by high quality digital microscopic photography; 7) preparation of figures for manuscripts; 8) storage and retrieval of stained slides for each of the projects. In addifion, this Core will be responsible for ordering, quality assurance and control studies of all anfibodies and reagents for use in the pathology methods. New reagents will be developed and evealuated as requested by investigators in the 3 projects.